KA67 brake upgrade suggestions and info required

[Ridal]

I'm going for cert so figured now is a good time to upgrade the brakes. I'll be taking the car to the track as much as I can.

 

Currently has standards everything which includes:

 

- KA67 struts with single pot calipers (140mm ish bolt spacing) on solid discs

- T series drum rear

 

Currently just has the 5K in it but I'd like to upgrade to something which would cope with more power in the future. I've already made a set of adjustable coilovers from some AA60 Carina struts so would like to still use those.

 

Any help is appreciated.

[Frosty]

The 3TGTE and 18RG powered Coronas, Carinas etc (RT140, TT140, RA60, RT60) used a larger vented rotor and a heaver shock (Same size as the GA70 but different geometry) and would be a bolt in as a complete replacement to the whole strut.

I don't know if the rotors would fit the unvented strut, you would have to check the wheel bearing sizes,rotor size and caliper position.

Pretty sure the wagons use a steering box and not rack and pinion as well so that may through up a whole lot of extra stuff.

You may be better of finding some MR2 twin pot calipers (SW20 NA use the same blot spacing as the Coronas) and using a custom rotor on the Coil overs you have made. Richard Pierce at Taranaki Brake and Clutch did some custom ones for my old RT86 Wagon at around $300 for a pair.

Back end is easy VR4 Galant or early Evo solid rotor rears require only a spacer between the axle flange and rotor and elongating the backing plate holes, the Toyota handbrake cables even fit into the Mitsi backing plate.

[Sambo]

Have you done that rear upgrade Frosty? Got pics? Would be interested to know more. I have the same setup in my SA60g.

[Frosty]

Yes I've done it but sadly no pictures.

Only works on the live Toyota diff not IRS.

Got my spacers made up by Specialist Engineering Services in Bell Block.

Only other bit needed was a 1mm shim behind the wheel bearing to compensate for the different thickness of the backing plate.

Because the Mitsi uses a small drum and shoe hand brake system you just fit the Toyota hand break cables into the backing plate.

 

Here's the way to do it.

Remove the old brakes, axle and backing plate.

Check the backing plate thickness against the Mitsi one, in my case (1973 RT87 Corona Wagon) it was 1mm thicker so I needed a 1mm shim to get the right depth for the wheel bearing.

Use the old backing plate to make a patten and transfer that patten onto the Mitsi backing plate and use a rat tail file to get the holes to line up (again this was only 1mm or so in my case).

Use the rat tale file to clearance the hole in the backing plate for the hand break cable or get the engineer to hone if as part of the job (Needed bugger all to get the cable to fit).

Get the axle, Mitsi backing plate bolted up and dummy fit the caliper and rotor to check how thick the spacer needs to be and record the measurement (5mm in my case)

Take the axle and rotor into the Engineers along with some measurements.

 

Spacer thickness for behind the Rotor.

Shim thickness for behind the Wheel bearing.

Wheel Bearing OD, OD for the shim.

Inner bore size for the Diff housing, ID for the shim at few mm bigger.

Thickness of the Rotor at the axle flange.

 

Then ask the Engineer to.

Remove the old Center bore location on the Axle.

Make up 2 Shims for behind the wheel bearing.

Make up two spacers using the OD of the axle flange, Center bore of the Mitsi rotor and the Toyota Center bore as the diameters and measurement for spacer thickness, rotor thickness and the old length of the Toyota Center bore locator as the 3 needed thickness and the stud holes to match your PCD for the wheels (114.3 x 4) and the two holes for the screws that will hold the spacer and rotor onto the axle flange (needed for cert)

Replace the old wheel studs with some new ones about 10mm longer.

Drill and counter sink the two holes needed in the rotor for the counter sunk screws needed (same reason as above and the same screws).

 

Please excuse my drawing.

 

 

Take the lot home and put it together and disc brakes on a live Toyota diff.

I did this and no one ever noticed at Wof time but it would comply for a cert as long as it's all screwed together at the axle flange and the center bore locators are correct.